Radioimmunoassay of 7 alpha-methyl-19-nortestosterone and investigation of its pharmacokinetics in animals.
A method for the measurement of 7 alpha-methyl-19-nortestosterone (7MENT) in serum/plasma by radioimmunoassay (RIA) is described. The antiserum, raised against 7 alpha-methyl-19-nortestosterone-3-O-oxime-bovine serum albumin, had a low titer (final dilution = 1:4500) and low affinity (Ka = 1.17 x 10(9) l/mol) but showed little or no cross-reactivity with several of the steroids tested. The sensitivity of the RIA was 28.2 pg/ml and the mean recovery of added cold steroid was 86 to 100%. Intra- and inter-assay coefficients of variation ranged from 4.3 to 7.3% and 7.3 to 8.4%, respectively. This RIA was used to follow plasma 7MENT levels after a single i.v. injection of the steroid in rats and rabbits. The metabolic clearance rates (MCR) of 7MENT as determined from the plasma disappearance curve for rats and rabbits were 50 l/day and 336 l/day, respectively. The MCR of 7MENT in rats and rabbits lies in the same range as for testosterone. When compared to other nortestosterone derivatives such as norethisterone, 7MENT is metabolized relatively faster.
Kumar
N
N
Center for Biomedical Research, Population Council, New York, NY 10021.
Didolkar
A K
AK
Ladd
A
A
Thau
R
R
Monder
C
C
Bardin
C W
CW
Sundaram
K
K
D000818:Animals; D004963:Estrenes / Q000097:blood* / Q000493:pharmacokinetics; D008657:Metabolic Clearance Rate; D009277:Nandrolone / Q000031:analogs & derivatives*; D011817:Rabbits; D011863:Radioimmunoassay / Q000592:standards / Q000706:statistics & numerical data; D051381:Rats
D004963:Estrenes; C064709:trestolone; D009277:Nandrolone